Grinding roll



P 1949. A. E. HAMILTON I 2,483,278

GRINDING ROLL Filed March 23, 1946 INVENTOR ALF/e50 HAM/L ro/v ATTORNEY Patented Sept. 27, 1949 I V V v, 5 i.- (i

GRINDING ROLL Alfred E. Hamilton, Pittsburgh, Pa. Application March 23, 1946, Serial-No. 656,724 I 5 Claims. (01. t -192) QMyfinvention relates to rolls for grindin and. polishing wood, metal, and other materials, including strips and sheets, and more particularly to rolls of the pneumatic type wherein air is maintained-under desired predetermined pressures to provide for desired degrees of grinding pressure, but certain features of the invention are applicable also to rolls of yieldable or compressible material such as sponge rubber.

In' making of surfacing drums of the pneumatic type, it has heretofore been common practice to incorporate therein reinforcing or restraining strips at axially-spaced points intermediate the ends of the drum, along circumferential lines, to support the intermediate, areas of the drum against too great radial stress or displacement under the internal air pressure or centrifugal force, since these intermediate areas do not have the benefit of the support afiorded at the ends of the drum by their walls. The result is that there are more or less defined circumferential areas some of which are, in effect, harder than the others, which tends to give a pattern or streak.

In some instances, abrasive-containing sleeves have been placed on the drums while the drumsare under no internal air pressure, but slight manufacturing differences. in the diameters of the sleeves sometimes give difficulty, because of danger of rupturing the sleeve when air, under working pressures, is introduced intothe drums; They frequently fail at the seam or lapwhere the ends of the strip are glued together to form the sleeve.

While helically-wound abrasive strips have been used on pneumatic drums, with their ends clamped at the ends of the roll, and they have been more satisfactory than the sleeves, in that they are readily adaptable to rolls of varying diameter, they still have not overcome the necessity for employing the circular reinforcing strips intermediate the ends of the drum. Furthermore. they have a' tendency to distort the drum on diagonal lines when air pressure is introduced into the drum.

One object of my invention is to provide surfacing rolls of the pneumatic or yieldable type wherein the advantages of the diagonally-wound strips over the abrasive sleeves are retained and certain other advantages secured that are not present with the use of the ordinary spirallywound drum. Among these advantages are:

(a) Strengthening the drum against radial displacement under centrifugal or pneumatic forces while avoiding danger of a pattern on the surfaced material, such as results from the use of circumferential stiffening; or restraining eleei may be mounted in the ments. b) Avoidance of or compensation for. distortion stresses diagonally of thedrum. i 1 (0) Provision for .chip clearance and disposal of the powder -like fines resulting from grinding. ((1) Provision for relatively stifier and softer areas at the periphery of the drum, which will render the drum more adaptable to non-planular surfaces on which the drum, operates, but wherein the stilfer and more flexible areas, respectively, alternate at anygiven zone circumferentiallyof the drum. j I Figure l is a face view-of a grinding'roll that. embodies my invention, and Fig. 2 is a fragmene tary, enlarged sectionalyiew of a portionof thestructure of Fig. 1. 7 i z.. y It will be understood that either a single roll may be employed, for surfacin one side of ,a; sheet or strip, or that a pair of the rolls can be used in opposed relation, to surface both sides of asheet simultaneously. Only so much of, the invention is shown as is required for,;an;under-; standing of theinvention. 'Apairof the rolls;

manner shown for example in my Patent 2,368,760;and;1luid pressure supplied to thepneumatic drumson the rolls in; the manner shown in my said patent; ,Ashaft 4 is mounted'in suitable bearingszand carries a pulley 5 by which the shaft will be driven from any suitable source of power. A hub fi issecured to the shaft and carries apneumatic drum 1 which is of flexible material such as rubber and contains an annular chamber 8 to which air under pressure may be supplied and maintained through a swivel coupling 9, a conduit: l0 inthe shaft 4, and a pipe ll during rotation of the drum, as described in my said patent. Strips 12. of tough paper or other flexible material are helically wrapped around the drum in one direction, .the successive helical turns being spaced apart a distance of perhaps one inch,. Abrasive, strips 13, which may be approximately 4 inches wide as in the drawing, are helically wrapped around the first-mentioned strips and the drums in the opposite direction so that the turns of the outer abrasive strips cross the turns of the strips 2| on diagonal'lines. This leaves the diamond-shaped spaces or pockets l4 adjacent to the points of crossing, of a depth equal to the thickness of the two layers of strips. The ends of the strips, or at least of the abrasive strips 13, are secured in any suitable manner to maintain them in wrapped condition, but I here show them turned backwardly and tucked in beor other suitable widths,

3 tween the periphery of the hub 6 and the inner surface of the drum 8, as shown at I in Fig. 2. The air pressure within the drum 1 will expand the drum, thus pinching or gripping the backturned ends of these strips and holding them in the drum against radial distortion either -Vunder centrifugal force or internal air pressure, anglhee ing along diagonal or helical lines','there are no circumferential zones of Varying degreesof'resist- ,T I

ance to deflection. Furthermore, these strips 12 being wrapped oppositelyto the abrasive strips ['3 counteract the tendency-oi the strips 13 todistort the drum along diagonal lines-when under working tension.

The diamond-shaped spaces or pocketsat l4, as well as the spaces between adjacent edges of the helically-woundstrips i3, serve as spaces to rewaive the, grindin'gsfrom the Work piece as well as the dustfrom worn' abrasive grains. Any grindings thataccumulate therein while passing over the work will be thrown clear'of the rolls as they are carried outof contact with the surface, of the-work.

Another feature of advantage resides in the, fact that the abrasive strips, under working pres sures, will be more flexible at points where they are in proximity to the edges of the underlying strips H, such asat Nix, than at the zones l1- intermediate such points 16, since the strips l2 will ofier greater-resistance to defiection'of the strips [-3 at the zones 17 than they willat the edges of'the strips l2. This not onlyenables the roll to operate more uniformly on surfaces that are not completely 'planular, but gives, in effect,

a two-grade-grinding action, since at the more resistant areas l1, there will be" greater grinding pressure than at themore'yieldable areas Him,

It will be understood-that the various advantages resulting from'the use of the oppositelywrapped strips 12 and I3,except for the matter of clip clearance w-ill be present also if these strips are closely wrapped on the drum'instead of having the adjacent edges of each set of'strips spaced apart as in Fig. l.

The drum is held against'slipping axially of the hub, when inflated, by the annular depression at Fain the hub, into which the rubber is swelled.

I claim as my invention: 1. A grinding roll comprising a hub, a flexiblywalled pneumatic drum on the hub, a restraining strip wound helically around the periphery of the drum, with a plurality of turns, an abrasive strip wound helically around the restraining strip and the-drum, with a plurality of turns and in a direction opposite to therestraining strip, and means '4 for securing the ends of the strips against displacement.

2. A grinding roll comprising a hub, a flexiblywalled pneumatic drum on the hub, a restraining strip wound helically around the periphery of the drum, with a plurality of turns, an abrasive strip wound helically around the restraining strip and the drum, with a plurality of turns and in a direction opposite to, the restraining, strip, and means for securing the ends of the strips aga nst displacement, the convolutions of each of the strips being spaced apart a substantial distance.

3. A grinding roll that is radially yieldable to a substantial depth in its peripheral portion, re-

straining elements having a plurality of turns disposed on generally helical lines adjacent to the periphery of the roll and arranged to resist radial expansion thereof, and an abrasive strip having a plurality of turns extending around the periphcral surface of the roll on helical lines in a direction approximately-opposite to the first-named lines;

4. A grinding roll' that is radially yiel'dabl'e to a substantial depth in its peripheral portion, restraining elements having a plurality ofturns disposed on generally helical lines adjacent to the periphery ofthe roll andarranged to resist radial expansion thereof, and an abrasive strip having a plurality of turns extending around the peripheral surface of the roll on helical lines in a direction approximately-opposite to the firstnainedlines; the convolutions of the said elements being spaced apart axially of theroll and the convolutions of the abrasive stripbeing spaced apart axially of the roll, the said spacing being lessthan one-half the width of the abrasive strips.

5; A grinding roll that is radially yieldable to. asubstantial depth in its peripheral portion, a restraining strip helically wound in a plurality of turns on the peripheral surface of the roll, and an abrasive strip'helically wound in a plurality of turns around therestraining strip in the'opposite direction, the convolutions of the restraining strip being spaced apart axially of the roll to thereby provide difierent degrees of resistance to grinding pressures imposed upon various areas of the abrasive strip ALFRED E; HAMILTON.

REFERENCES CITED- The following references are of record in the.

file of this patent:

UNITED STATES PATENTS 

